Induction motor starting relay



Nov. 15, 1948. PRQUTY r 2,453,726

INDUCTION MOTOR STARTING RELAY Filed April 4, 1945 2 Sheets-Sheet l 4 lr ll 7 96 Z2 22 107 i 49 w 12 2 g E 93 52 10 12 g 59 88 18 w W 11 l 2 132.

r HA G9) I o 8 g}. 7 2 29 R Q i O Q 0 i9 W 5 10 I 75646222 @212 Q g; '00 5 0 4 INVENTORS. 15 l5 JZQb-QTZEPTQLLQ Nov. 16, 1948. R. E. PROUTYarm. 2,453,726

INDUCTION MOTOR STARTING RELAY Filed April 4, 1945 2 Sheets-Sheet 22INVENTORS. Raert EProuy MMTLZZ. Qdams;

Patented Nov. 16, 1948 2,453,726 INDUCTION MOTOR STARTING RELAY RobertE. Prouty,

Flora,

assignors, by mesne as and Richard L. A

Logansport, Ralph E. Bish, dams, Logansport, Ind., signments, to EssexWire Corporation, Logansport, Ind., a corporation of MichiganApplication April 4, 1945, Serial No. 586,596

17 Claims. 1 Our invention relates to an improvement in a relay, andmore particularly to a relay for starting and controlling an electricmotor.

The great difiiculty with most motor starters of the prior art is thatthey require brushes which are thrown off by centrifugal force after themotor has reached a predetermined speed to cut out a starting winding,or are provided with wiping contacts for that purpose both of which aresubject to wear or become injured in use so that after a limited numberof operations the brushes or wiping contacts do not perform as intendedand the motor is unable to start.

It is an object of our invention to provide a relay type of contact forwhich will operate without substantial wear or being subject to injuryfor an enormous number of operations.

A further object of our invention is to provide a relay for use with anelectric motor having a running winding and a starting winding in whichthe relay comprises normally closed contact means adapted to beconnected in circuit with the starting winding, and means including atuned reed responsive to a predetermined speed of rotation of the motorto open the normally closed contact means and thereby open the circuitof the starting winding.

In order to accomplish these objects we propose to provide a tuned reedfixed at one end and associated with the motor to be controlled so thatthe reed vibrates due to speed of rotation of the motor, and which reedin the embodiments of the invention herein disclosed comprises, in part,an armature for an electromagnet. The reed is adjusted to vibrate inresonance at a predetermined frequency and carries-a contact which isadapted to have contacting engagement with a second contact carried by asuitable flexible contactor. These two contacts are adjusted to benormally opened. A holding coil or electromagnet is provided for thearmature of which the reed forms a part, and the normally open contactsand the coil of the electromagnet are connected electrically with asuitable current supply. A single pole mechanical switch having normallyclosed contacts is mounted adjacent the flexible con tactor and one ofthe normally closed contacts of the switch is positioned to be actuatedby movement of the flexible contactor when the latter is caused to beflexed by attraction of the armature to separate the normally closedcontacts and open the mechanical switch. The flexible contactor isadjusted to have limited free movement before it opens the normallyclosed contacts of starting an electric motor the mechanical switchwhich are connected in series electrically with the starting winding 01'the motor. 7

In such a device when a main control switch for the motor is closedsupply voltage is applied to the motor and current flows in the runningwinding and the starting winding and through the normally closedcontacts of the mechanical switch. However, current does not flow in theelectromagnet for the armature of which the tuned reed forms a part,because the circuit is open due to the normally opened contacts of thereed and flexible contactor. As the motor starts to run and the speedbuilds up, the motor reaches a predetermined speed which is equal to theresoe nant frequency of the reed causing the reed to vibrate withsufflcient amplitude to close the normally opened contacts. This closingof the normally open contacts energizes the electromagnet and attractsthe armature causing the same to engage the flexible contactor and openthe normally closed contacts of the mechanical switch. Since thesenormally closed contacts are in series with the starting winding openingof them causes opening of the starting winding circuit and the motorcontinues to run on the running winding only.

A preferred feature of one form of the invention herein disclosed is inconnecting the aforesaid electromagnet in parallel relation with therunning winding so that the electromagnet maintains the startin windingcircuit open until the main control switchfor the motor'is opened. Itthe main control switch is opened the electromagnet will bedeenergizedreleasing the armature, and the relay is set for anotherstarting cycle.

A further preferred feature of another embodiment of the invention is inproviding the aforementioned electromagnet with a pair of coils one ofwhich is adapted to be connected in series relation and the other inparallel relation with the running winding of the motor with the coil inseries relation being operable during momentary overloads on the lineand running winding to neutralize the magnetic effect of the coil inparallel relation to release the armature and cut the starting windingin circuit.

A further preferred feature which may be incorporated with either of theembodiments of our invention herein disclosed resides in the pro-.

vision of an additional electromagnet and an armature therefor connectedin series relation with the starting and running winding of the motorserving as a cutout for the electric motor in the event of a continuousoverload on the line. The armature of this last referred toelectromagnet is provided with a contact having engagement with acontact carried by a bi-metal strip which strip is adapted to flex uponheating due to overload to' separate the contacts, which when thatoccurs opens the circuit in advance of the electromagnetic means firstabove discussed.

The relay is also of simple construction providing a device which is oflow cost permitting its use in a wide number of installationsparticularly for small motors for use, for example, with refrigeratorsand other apparatus.

Other object and advantages of our invention will appear from the detaildescription.

Now, in order to acquaint those skilled in the art with the manner ofutilizing and constructing relay-s in accordance with our invention, weshall describe in connection with the accompanying drawings certainpreferred embodiments invention.

In the drawings:

Figure 1 is a side elevational view of a relay constructed in accordancewith our invention with the housing therefor being shown in section;

Figure 2 is a bottom view of the relay in the position shown in Figure 1taken substantially on the line 2-2 of Figure 1, looking in thedirection indicated by the arrows;

Figure 3 is a side elevational view of the other side of the relay ofFigure 1, taken substantially on the line 33 of Figure 2, looking in thedirection indicated by the arrows;

Figure 4 is a bottom view of the device in the position shown in Figure3;

Figure 5 is an end view of the relay of Figures 1 through 4, which hasbeen taken substantially on the line 5-5 of Figure 3, looking in thedirection indicated by the arrows;

Figure 6 is an end view of the relay of Figures 1 through 4, takensubstantially on the line 6-6 of Figure 3, looking in the directionindicated by the arrows;

Figure '7 is a circuit diagram of the relay of Figures 1 through 6 andshowing its connection with the windings ofan electric motor and asource of current supply; and

Figure 8 is a circuit diagram of a modified form of relay of ourinvention.

Referring now to Figures 1 through 6, we have shown a housing Inpreferably made of insulating material and which is of rectangular shapein plan. A partition ll preferably formed integrally with the housing Inextends lengthwise thereof between the end walls l2 and the bottom walll3. The device will be described assuming that it is to be mounted on amotor frame in the position shown in Figure 1 so that the wall l3 may beconsidered to be the bottom wall of the housing and the housing beingopen at its upper end. It is to be understood, however, that the deviceand housing may be mounted in any position desired without affecting theproper operation of the relay. The partition I I extends from the bottomwall I3 of the housing substantially midway thereof. One end wall l2 andone side wall of the housing are provided with openings through whichthe leads (not shown) for the relay extend into the housing. It will beunderstood that a suitable closure member may be provided for closingthe open upper end of the housing, and this may comprise a removablecover member, or a wall of a motor frame or the like which the relay isto control. It is to be understood that the housing In and the relaytherein is associated of our with the motor in a manner so that theoperation of the relay in starting of the motor is controlled byvibration produced by the motor. Any suitable mounting means for thehousing in may be provided and it can be mounted either externally orinside the motor frame as required by the expediency of the situation towhich the motor is to be put.

The relay indicated generally at l8 comprises a substantiallyrectangular base IQ of insulating material, and which base is formedwith a rib 20 integral therewith extending lengthwise thereof and ofthehousing l0, and intermediate the front and rear edges of the basemember 19 so that the rib 20 lies vertically in alignment with thepartition ll of the housing. The end walls l2 of the housing 10 areformed with shoulders 22 over which the end edges of the base member l9extend providing an overlap of the base member I9 therewith to insulatethe leads extending through the openings l5 of the housing from theparts of the relay positioned in the housing between the bottom wall l3and the base member iii. A core frame member 23 substantially ofE-shape, as viewed in plan (Figure 2) is secured to the base member 49by a pair of bolts 24 which extend through the rib 20 and into thepartition I! of the housing to. The outer leg elements 26 and 21 of thecore frame member 23 provide core sections for a pair of coils 29 and30, respectively, to support the coils 29 and 30 to extend with theiraxes in parallel relation with each other and lengthwise of the housingill. The core 21 and coil 30 comprise parts of electromagnetic means 32which, as will hereinafter appear, serves to cut out the relay i8entirely upon a continued overload on the supply line, and theelectromagnetic means comprising the core 26 and coil 29 comprise anelectromagnetic means 33 which is for the purpose of cutting out thestarting winding of the motor after it has reached a predeterminedspeed, as will be described in detail hereinafter.

A plurality of terminals 35, 36, 31, 38 and 33 are carried by the basemember l9 along the margins of its front and rear edges providing forconnection of the electromagnets 32 and 33 with a source of currentsupply and to leads of the motor to be controlled. These terminalmembers are all of like construction, and the terminal 35, as belowdescribed, is typical of the construction of all of them. As shown inFigures 3 and 5, it will be observed that the terminal 31 comprises asubstantially U-shaped clip 42 which snugly fits over an edge of thebase member l9 and the leg portion thereof inwardly of the housing I3,is formed with a pair of up struck ears 44 which have threadedengagement with a bolt 46 having a head 41 at one end thereof providedwith the usual kerf for rotating the same with a screw driver or likeimplement. The electrical connections are made between the terminals andthe several leads of the electromagnetic means 32 and 33 by securingsuch leads as by soldering to the clip members 42. The leads from themotor and the current supply source are adapted to be made between thebolt heads of the several terminals and the outer legs of the clips. Theterminals 35 and 36 provide for connection of the relay l8 with a sourceof current supply, and it will be observed from Figures 3 and 5 that alead 48 extends from the terminal 35 to one end of the coil 30 of theelectromagnetic means 32. A lead 49 (Figure 3) extends from the otherend of the coil 30 to a terminal 50 formed by a clip 42, as previouslydescribed. This terminal is not adapted to have connection with anyoutside lead and simply provides for electrical connection of the lead50 from the coil 30 to a metal heater strip member 53 one end of whichis connected to the clip. The heater strip member 53 is connected at itsother end to the inturned ear 54 of a substantially C-shaped bracket 55,the Other ear or leg 56 of which is suitably secured to the base memberI9 by a bolt 51. A bolt 58 having threading engagement with the leg 56of the bracket 55 engages the other leg or ear 54 of the bracket. A leafspring 59 of bi-metal is suitably connected at one end to the car 54 ofthe c-shaped bracket 55 and at its other or free end carries a. contact60. The contact 60 has normally closed engagement with a contact 6|carried by an armature 62 which armature is adapted to be attracted uponenergization of the coil 30 of the electromagnetic means 32. Thearmature 62 comprises a first metal arm member 64 riveted at one end toa thin metal strip 65 which is fixed as by riveting at its other end toan ear 66 formed at the free end of the intermediate leg 25 of the coreframe member 23. The free end of the arm 54 is bent substantially atright angles to form the extension or armature bar 68 which is adaptedto be attracted upon energization of the coil 30. An arm 61 is rivetedatone end to ear 66 of the leg 25 and at its free end carries a bolt 11which has threaded engagement with the leg 25 of the core frame member23 and provides for adjustment of the armature 62 by flexing of ear 66.The leg 25 of the core frame member 23 has a bracket 14 suitably securedat one end thereto, the other end of which has a laterally extending ear15 which overlies the extension or bent end 68 of the arm 64 of armature62 to limit the upward movement of the armature when the coil 30 isdeenergized. As shown in Figure 3, the partition I I of the housing I isformed with a substantially triangular recess 11 for accommodating thebracket 14. A bolt 19 extends through the free end of bracket 14 and hasthreading engagement with the leg 25 which provides for adjustment ofthe ear of the bracket relative to the extension 68 of the armature 62.

Referring now more particularly to Figure 1, it will be observed thatthe electromagnetic means 33 has an armature 85 associated therewithwhich comprises an armature metal bar member 86 secured at one end as bya rivet to a thin spring steel reed 81 the other end of which isconnected as by a rivet to an ear 88 of the leg 25 of the core framemember 23 extending laterally opposite the car 66. An arm 89, like arm61, is riveted at one end to ear 88 and it also is provided with a bolt92 at its free end having threading engagement with the ture by flexingof ear 88. The bar 86 of the armature 85 carries a contact 90 adjacentits free end. A thin metal flexible contactor arm member 9| is fixed atone end to a C-shaped bracket 93, like the bracket 55 previouslydescribed, and it is suitably fixed to the base member I9 by a bolt 94.A bolt 95 has threading engagement with the leg 96 of the bracket 93,and the end of the bolt is adapted to engage the other leg 91 of thebracket 96 providing for adjustment of the position of the metalcontactor arm 9|. The spring arm 9| at its free end carries a contact 98in a position to be engaged by the contact 90 of the armature 95. Thecontacts 90 and 98 are normally open. As shown more clearly in Figure 1the terminal 39 is connected by a suitleg 25 for adjustment of thearmabar 53 with the bi-metal able lead I00 to a bracket I 0| fixed atone end as by riveting to the base member I9 and carrying a contact I02at its other end. The contact I02 has normally closed engagement withthe contact I03 carried by contact arm I04 which is connected at its endopposite the contact I03 with the free end of the core leg 26 of thecore frame member 23.

A lead I01 extends from the core frame mem ber 23 to the clip 42 ofterminal 31. A lead I08 extends from one end of the winding of coil 29to the terminal 38, and the O-shaped bracket 93 has a lead I09 extendingfrom the end of leg 96 thereof to the other end of the winding coilmember 29.

Any suitable electrical connection is provided between the terminals 36and 38, and upon reference to Figure '7 it will be observed that amanually operable switch IIO has been interposed between a lead I09connecting the terminals 36 and 38. This switch structure is not shownin Figures 1 through 6. The incorpora tion of such switch however, maybe readily made by a skilled workman and may be disposed in any suitableposition and provides for opening or closing of the circuit between theterminals 35 and 36 to cut the relay in and out of circuit with a supplyline.

Referring now to Figure 7, we have shown the electrical circuit of therelay above described in connection with Figures 1 through 6, and theseveral parts and leads of the relay are indicated by like referencenumerals. Figure 7 in addition shows the connection of the terminals 31,38 and 39 of the relay of our present invention with the windings of anelectric motor. The electric motor is indicated by the reference numeralI20 and it comprises a starting winding I2I and a running winding I22.The starting and runing windings are arranged in parallel and haveconnection with the terminal 38 by a conductor I23, with the other endofthe running winding I22 being connected by the lead I24 with theterminal 31 of the relay above described. The other end of the startingwinding I2I is connected by a conductor I25 to terminal 39 of thepreviously described relay.

With the circuit connections of the relay being made as described withthe electric motor I20, shown in Figure '1, the operation of the deviceis as follows:

The terminals 35 and 36 are connected to current supply leads I 30 andI3I, respectively, and the leads I 23, I24 and I25 are connected toterminals 38, 39 and 31, respectively, as previously described. Fromterminal 35 the current is conducted by the lead 48 to the coil 30 ofthe electromagnetic means 32 therethrough and from the conductor 49 tothe terminal 50, and from the latter to the heater bar 53. The bracket55 provides an electrical connection of the heater spring member 59,

' thence through normally closed contacts 60 and 6|, armature 62 to leg25 of the core frame member 23. The leg 25 of the core frame member 23serves as a conductor and from which the lead I 01 extends to terminal31. The conductor I24 extends from terminal 31 to one end of runningwinding I22, the other end of which is connected by lead I23-to leadI09, switch H0 and terminal 36 to complete the circuit through therunning winding. The flexible carrier member I04 also has connectionwith the terminal 31 through leg 26 of core frame member 23 and thecontact I03 carried by member I04 has northe mally closed contactingengagement with the contact I02, which is connected by the bracket; IMand lead I to the terminal 38 from which lead I extends to one end ofthe starting winding I2I. The other end of the starting winding isconnected by the conductor I23 to the terminal lead I09, switch H0, andterminal 36. When the switch IIO between the terminals 36 and 38 isclosed the electromagnetic means 32 is energized attracting the armature62 which flexes the bi-metal element 58 downwardly with the armature tomaintain pressure contact between the normally closed contacts SI and 50to per: mit current flow through the running winding I22 and thestarting winding I2 I of the motor to start the same. The contacts 00and 88 are normally open and therefore upon closing of switch IIO, theelectromagnetic means 33 is not energized. Now, when the motor reaches apredetermined speed so that it sets the reed 81 of the armature 86 tovibrate in resonance to apredetermined frequency, the reed will vibratewith suflicient amplitude to close the normally open contacts 00 and 98.This closing of the contacts 90 and 98 energizes the coil 29 of theelectromagnetic means 33 which attracts the armature 85 engaging thespring'contactor arm 9| which then engages flexible member I04 andmoving the contact I03 carried thereby away from the contact I02, ingwinding so that the motor continues to run on the running winding only.Thereafter the electromagnetic means 33 will maintain the startingcircuit open until the main control switch H0 is opened or the normallyclosed con tacts 60 and BI of the cutout relay are caused to beseparated. If the main controlswitch H0 is opened the coil 29 of theelectromagnetic means 33 is deenergized releasing the armature 86 andthe switch is set for another starting cycle.

The electromagnetic means 32 provides a safety cutout mechanism for therela and it will be observed in the physical arrangement of parts asshown in Figure 3 that if a load is placed upon a line or a shortcircuit occurs the bi-metal element 59 will heat up causing it to snapaway from the armature 62 to thereby separate the contacts 62 which inits attracted position is maintained substantially in lengthwisealignment with the axis of coil and BI from each other which opens thecircuit between the terminals and 36. When this condition occurs it willdeenergize the electromagnet 32 and open the circuit through thewindings of electric motor I20. After the bi-metallic element 59 hascooled it will again return to the position shown in the drawingswherein the contacts 60 and 6| are reengaged to again establish acircuit through the running and starting windings which, after motor hasreached a predetermined speed, the normally closed contacts I02 and I03,are opened, and the normally open contacts 90 and 38' are closed toopen the circuit of the starting winding.

In Figure 8 we have shown a modified form of relay and circuitarrangement therefor. In this modified embodiment of the relay and ofcircuit arrangement the electromagnetic means 33' comprises a coil 29'connected by conductor I08 to the lead I09. The electromagnetic means33' also includes a series coil winding I32 connected in series by leadsI33 and I30 with the running winding I22. Now when heavy currents passthrough the running winding I22, such as occur during momentaryoverloads on the line, the

and opening the circuit of the startseries coil I32 will partiallyneutralize the electromagnet means 33' causing the armature 88 to bereleased and thereby close contacts I02 and I03 so that the startingwinding I2I is again out into circuit. When the overload is removed andthe motor again attains its predetermined speed the starting winding I2Iwill be cut out'in the manner previously described. For purposes ofillustration the series coil I32 has been shown spaced away from thecoil 29' of the electromagnet means 33, but it will be understood thatin the preferred embodiment of the form of our invention that the seriescoil I32 is wound around the coil 29.

While we have shown what we consider to be the preferred embodiments ofour invention, it will be understood that various modifications andrearrangements may be made therein without departing from the spirit andscope of the invention.

We claim:

1. A device for use with an electric motor having a running winding anda starting winding comprising contact means adapted to be connected incircuit with said starting winding, electromagnetic means including atuned reed armature, said tuned reed armature being adapted to vibrateresponsive to vibration of said motor at a predetermined speed ofrotation thereof, said tuned reed armature upon vibration thereofeffecting energization of said electromagnetic means, saidelectromagnetic means when energized being adapted to attract said tunedreed armature, and s id tuned reed armature in its attracted positionproviding for opening said normally closed contacts.

2. The combination with an electric motor having a running winding and astarting winding, of a relay comprising normally closed contacts adaptedto be connected in the circuit of said starting winding, anelectromagnet, a tuned reed armature for said electromagnet, said tunedreed armature being adapted to vibrate responsive to vibration of saidmotor at a predetermined speed of rotation thereof, said tuned reedarmature upon vibration thereof effecting energization of saidelcctromagnet, said electromagnet when energized being adapted toattract said tuned armature and said tuned reed armature in itsattracted position providing for opening said normally closed contactsof said relay.

3. The combination with an electric motor comprising a running windingand a starting winding, of a relay comprising normally closed contactsadapted to be connected in the circuit of said starting winding,electromagnetic means including a tuned reed armature and normally opencontact means opening the circuit of said electromagnetic means, saidtuned reed armature being adapted to vibrate responsive to vibration ofsaid motor at a predetermined speed of rotation thereof, said tuned reedarmature upon vibration thereof being adapted toefi'ect closing of saidnormally open contacts to energize said electromagnetic means, saidelectromagnetic means when energized being adapted to attract said tunedreed armature, and said tuned reed armature in its attracted positionproviding for opening said normally closed contacts.

4. The combination with an electric motor having a running winding and astarting winding, of a relay comprising normally closed contacts adaptedto be connected in circuit with said starting winding, an electromagnet,and a tuned armature adapted to be attracted by said electroma net,normally open contacts associated with said armature and electromagnet,said armature being responsive to a predetermined speed of rotation ofsaid motor to close said normally open contacts and thereby energizesaid electromagnet, said armature upon being attracted by saidelectromagnet causing opening of said normally closed contacts andthereby open the circuit of said starting winding.

5. A starting relay for use with an electric motor having a runningwinding and a. startin winding connected in parallel relationcomprising, an electromagnet adapted to be connected in parallel withsaid windings and having normally open contacts whereby saidelectromagnet is normally de-energized, a tuned reed armature adapted tobe attracted by said electromagnet upon energization of the latter, saidtuned reed armature being adapted to vibrate responsive to vibration ofsaid motor at a predetermined speed of rotation thereof, said tuned reedarmature upon vibration thereof eflecting closing of said normally opencontacts for energizing said electromagnet, normally closed contactsadapted to be connected in the circuit of said starting winding. andsaid tuned reed armature in its attracted position providing for openingof said normally closed contacts to open the circuit of said startingwinding.

6. A relay for use with an electric motor having a running winding and astarting winding comprising, an electromagnet having a pair of coils,one of said coils being adapted to be connected in closed seriesrelation with said running winding, and the other of said coils beingadapted to be connected in parallel relation with said running winding,normally open contact means between said other of said pair of coils andsaid running winding, normally closed contact means adapted to beconnected in the circuit of said starting winding, and means responsiveto a predetermined speed of rotation of said motor for closing saidnormally open contacts to energize said other coil of said electromagnetin parallel with said running winding causing opening of said normallyclosed contacts and thereby opening the circuit of said startingwinding.

7. A relay for use with an electric motor having a running winding and astarting winding comprising, an electromagnet having a pair of coils,one of said pair of coils being adapted to be connected in closed seriesrelation with said running winding, and the other of said pair ofcoilsbeing adapted to be conntected in parallel relation with said runningwinding, normally open contact means between said other of said pair ofcoils and said running winding, normally closed contact means adapted tobe connected in the cir-' cuit of said starting winding, and meansresponsive to a predetermined speed of rotation of said motor forclosing said normally open contacts to energize said other coil of saidelectromagnet causing opening of said normally closed contacts andthereby open the circuit 01' said starting winding, said one coil ofsaid electromagnet upon overload current flow in said running windingrendering the magnetic effect of said other coil ineffective wherebysaid normally closed contacts when opened are re-closed to reestablishsaid starting winding circuit.

8. In a relay for use with an electric motor having a running windingand a starting winding, an electromagnet comprising a pair of coils onebeing adapted to be connected in series relation and the other inparallel relation with said running winding, a tuned armature for saidelectro- 10 I magnet, normally open contact means adapted to beconnected in the circuit of said other coil, normally closed contactmeans adapted to be connected in the circuit of said starting winding,said tuned armature being responsve to a predetermined speed of rotationof said motor for closing said normally open contacts to energize saidother coil of said electromagnet and attract said armature, saidarmature in its attracted position causing opening of said normallyclosed contacts of the circuit of to deenergize the latter.

9. In a relay for use with an electric motor having a running windingand a starting winding, an electromagnet comprising a pair of coils onebeing adapted to be connected in'series relation and the other inparallel relationwith said running winding, a tuned spring metalarmature for said electromagnet, contact means in the circuit of saidother coil and associated with said electromagnet and said armature andnormally maintained in open relation by said armature in its releasedposition, normally closed contact means adapted to be connected in thecircuit of said starting winding, said armature being responsive to apredetermined speed of rotation of said moe tor for closing said firstcontact means to energize said other coil of electromagnet, saidarmature in its movement to its attracted position causing opening ofsaid normally closed contact means and thereby opening the circuit ofsaid starting winding, said one coil of said electromagnet upon anoverload thereon and on said running winding neutralizing the magneticeffect of said other coil and permitting said armature to return to itsreleased position whereby said normally closed contacts are reclosed toreestablish said starting winding circuit.

10. A relay for use with an electric motor having a running winding anda starting winding comprising, an electromagnet adapted to be connectedin tuned spring metal armature, normally open contact means comprising apair of contacts one of which is carried by said armature, a flexiblecontactor arm fixed at one end and carrying the other of said pair ofcontacts, contact means comprising a pair of normally closed contactsadapted to be connected in the circuit of said starting winding, aspring contact arm carrying one of said normally closed contacts, saidflexible contactor arm being arranged to lie between said armature andsaid spring contact arm, said armature being responsive to apredetermined speed of rotation of said motor to vibrate with sufllcientamplitude to close said normally open contacts carried by said armatureand said flexible contactor arm whereby said electromagnet is adapted tobe energized, said armature in its movement to its attracted positionengagingsald flexible contactor arm with said spring contact arm toseparate the normally closed contact carried thereby from the otherclosed contact and open the circuit of said starting winding.

11. The relay of claim 10 characterized by the electromagnet comprisinga coil adapted to be connected in parallel relation with the runningwinding of the motor.

12. The relay 01' claim 10 characterized by the electromagnet comprisinga pair of coils one being adapted to be connected in series relation andthe other in parallel relation with said running winding.

13. The relay of claim 5 characterized by the provision of a secondelectromagnet, an armature said starting. windingv circuit with saidrunning winding, 8.

said starting winding,

therefor, a bi-metal member, and normally closed contacts carried bysaid armature and said himetal member for connecting said secondelectromagnet in series relation with said first electromagnet and thewindings of the motor, said himetal member upon overload current passingtherethrough being adapted to flex away from said last named armature toseparate said last named normally closed contacts.

14. The relay of claim 8 characterized by the provision of a secondelectromagnet, an armature therefor, a bi-metal member, and normallyclosed contacts carried by said armature and said himetal member !orconnecting said second electro magnet in series relation with said firstelectromagnet and the windings of the motor, said bimetal member uponoverload current passing therethrough'being adapted to flex away fromsaid last named armature to separate said last named normally closedcontacts.

' 15. The combination with an electric motor having a running windingand starting winding,

.of a relay comprising normally closed contact means adapted to beconnected in the circuit of said starting winding, and electromagnetmeans adapted to be energized upon a predetermined speed of rotation ofsaid motor for opening said contact means and thereby open the circuitof a second electromagnet means comprising an armature and a bi-metalmember, normally closed contacts carried respectively by said armatureand bi-metal member for connecting said second electromagnet means inseries relation with the first mentioned electromagnet means and thewindings of the motor, said bi-metal member being connected in serieswith said normally closed contacts and upon overload current passingtherethrough being adapted to flex away from said last named armature toseparate said normally closed contacts.

16. In a device for use with an electric motor having a running windingand a starting winding comprising, normally closed contact means adaptedto be connected in circuit with said starting winding, an electromagnetadapted when energized to open said normally closed contact means,normally open contact means in circuit with said electromagnet, a tunedreed associated with said normally open contact means adapted upon apredetermined speed of rotation of said motor to effect closing of saidnormally opened contact means to energize said electromagnet, saidelectromagnet when energized being adapted to attract. said tuned reedto maintain said normally closed contacts open.

1'7. In a device for use with an electric motor having a running windingand a starting winding comprising, normally closed contact means adaptedto be connected in circuit with said starting winding, an electromagnetadapted when energized to open said normally closed contact means,normally open contact means in circuit with said electromagnet, a tunedreed associated with said normally open contact means adapted upon apredetermined speed of rotation of said motor to effect closing of saidnormally open contact means to energize said electromagnet, saidelectromagnet when energized being adapted to attract said tuned reed tomaintain said normally closed contacts open, and said electromagnethaving means adapted upon predetermined overload current flow in saidrunning winding for releasing said tuned reed whereby said normallyclosed contacts when opened are reclosed to reestablish said startingwinding circuit.

ROBERT E. PROUTY. RALPH E. BISH. RICHARD L. ADAMS.

REFERENCES CITED The following references areof record in the file ofthis patent:

UNITED STATES PATENTS Name Date Bogen June 18, 1912 Peaslee Sept. 21,1926 Heinrich Aug, 15, 1933 Werner Feb. 12, 1935 Werner May 10, 1938McCormick Mar. 10, 1942 Stimson Sept. 15, 1942 Ogden et al Mar. 16, 1943Number

